Inflation in two bodies doesnt look like a single body
 

Hi all,

I would like find out why inflation in two bodies doesnt look like a single body. At the attached two screenshots are seen. I have done one part including two bodies.

Hint: Second one has the problem

Any knowledge, or thought?

Kind Regards,

i could find the problem in second pic.
What issue do you have? sorry i couldnt figure it out

I am using 14.5 version I couldnt see multibody inflation. But I have done by selecting two bodies in geometry and wetted faces of interest in inflation tab.

Well, thank you, as you can see there is no layer compression because of the place two bodies contact

What? I gave you link on flash video where it is shown how to get consistent inflation on multiple bodies. Have you watched it?

Thank you Antanas,

I couldnt realize that it was a link


Kind Regards,

I have watched the video. It is very different from thing I would like to make .

Please check watchfully regarding two screenshots. One of them has a layer compression in nozzle but the other one has an abrupt because of having two bodies. Inflation layer should follow like a single body. So, I need to split single body in order to see what some interior face values have in FLUENT. Inflation mesh couldnt like before.

I hope you understand what problem is

Kind Regards,

Just do mesh like on image. You can't make inflation layers to flow between bodies with this angles.

I really dont understand, inflations should be given in boundary layer regions. It shouldnt be given joint of two bodies.That is my thought. Velocity in fluid flow must not be 0 there or decreased by shear stress . That is what, layer compression screenshot is correct, one way or another.

the attahced one.

Hi. If I understand, you don't want 2 boundary layers in area you have indicated? Because I don't know whole geometry..

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yes, there is no a single body, I have splitted to two that's why, two successive boundary layer occurs.

Some time ago, I have the same problem with my model of combustor (1 body) and let's say measurement domain (2 body). I had to create transition boundary layers for one duct. I did it in ANSYS Meshing module in Workbench using selective meshing if I remember correctly. Are you also using Workbench for this study?

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yes, I am using ANSYS-Meshing,as well.

Are there prism layers near walls? Yes, there are. So what's the problem?

Ok, so selective meshing should help you. Firstly insert inflation option on one body which is primary and then insert inflation at second body. You have to do it separately. After that, do the same with creating meshing: First click right bottom on primary body and select meshing on selected body... and when mesh is created do the same on second body. Consequently, second mesh should be depend on first mesh.

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ozcaan, here is more explanation about it: https://www.sharcnet.ca/Software/Ans...b_meshing.html

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This won't help him.

Why do you think so?

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Thank you both

I am going to try what you told as soon as possible.

I am going to let you know

Because of the angles between bodies the algorithm cannot continue with the inflation layer from one body to into another there. Stair stepping will occur at the intersection.

The inflation mesh is generally made in wall-bounded models. Attached screenshot tells us that one of them is wall the other wall is fluid flow domain or the opposite way round. As I said before, the correct meshing like this models (single fluid domain having two bodies.) should be in first screenshot (layer compression)

Velocity magnitude in that nozzle must be maximum,especially in nozzle center.
Kind Regards,

Ok, maybe you have right because I didn't meet this in my study.

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Really? So you wanna say that mesh on the image below is wrong? Because based on your words there're walls everywhere. :D

Thank you mate ;)

Do you have any suggestion in ''view advanced options'' to avoid stairstep ?

like max. angle, fillet ratio, fix first layer, gap factor ?

Kind Regards,

They won't help in your case. Watch video that I gave you again, pay attention to text notes. It is very useful.

Thank you in advance,

I have watched it, it tells that max. angle should be increased to avoid stair-step in inflation. I have already done so, and defined it 175 degree, but ,it doesnt work . That is why, I have asked it

There're 3 different situations (3 locations) there and 3 different workarounds. Read notes carefully again.

ok thank you